1. Technical Field of the Invention
The present invention relates generally to the measurement of digital signals; and, more particularly, to a method and apparatus for determining characteristics of a digital data signal utilizing Eye Diagram analysis.
2. Description of Related Art
Eye Diagram analysis is an important tool for studying the behavior of high-speed digital electrical and optical communications signals. An Eye Diagram is a way of displaying, on an oscilloscope or other suitable display device, a composite image of the waveform shapes of logic one-zero combinations of a digital data signal. An Eye Diagram is generated on an oscilloscope by applying the waveform to the vertical channel of the oscilloscope while triggering from a synchronous clock signal at, for example, the data rate of the digital signal Eye Diagrams of high speed digital signals are often generated using an equivalent-time sampling oscilloscope (e.g., the Agilent Technologies 86100B sampling oscilloscope). By measuring features of the generated Eye Diagram, various characteristics of a digital data signal, such as signal-to-noise ratio, extinction ratio, jitter, duty cycle distortion, and the like, can be readily determined.
The construction of a complete Eye Diagram may require from 200,000 to 1,000,000 samples, and tens of seconds may be required to acquire this amount of data. Such a length of time can negatively affect the efficiency and profitability of component and system manufacturers and others that use Eye Diagram analysis.
There is, accordingly, a need for a method and apparatus for efficiently determining characteristics of a digital data signal using Eye Diagram analysis.